How do I seprate a plot based on a value of the y axis

I plotted a curve and needed to seperate it based on weather the y axis exceed a limit. I added a horziontal line at the limit of the y axis, to the plot of the curve. I think it matters that I used pchip and ppval to create my curve ,rather than an actual polynmial. This means when I try finding the intersect with methods such as the intersect funtion, I am returened with a blank array. I am not sure how I can get matlab to simpily just output the intersect efficently , if possible. Note splitting the array of the y values could be hard since it consists of more then 10000 values.

Answer 1

[Bryan]

you can get the current y axis limits using ylim, and then evaluate them to decide if you want to split the axis or not

limitvalue = 100;

if max(ylim) > limitvalue
    % your code for splitting axis goes here
end